U.S. patent number 6,522,024 [Application Number 09/868,865] was granted by the patent office on 2003-02-18 for output state detector for internal combustion engine.
This patent grant is currently assigned to Toyota Jidosha Kabushiki Kaisha. Invention is credited to Katsuhiko Hirose, Toshio Inoue, Hiroshi Kanai, Masakiyo Kojima, Masaki Kusada, Takahiro Nishigaki, Toshifumi Takaoka, Katsuhiko Yamaguchi.
United States Patent |
6,522,024 |
Takaoka , et al. |
February 18, 2003 |
Output state detector for internal combustion engine
Abstract
An output state detecting apparatus is arranged to detect a
reaction torque of a motor and detect an output state of an
internal-combustion engine from the reaction torque. The apparatus
comprises an internal-combustion engine, a generator driven by the
internal-combustion engine to generate electric power, torque
detecting means for detecting a reaction torque of this generator,
and output state detecting means for detecting an output state of
the internal-combustion engine. The output state detecting means
detects the output state of the internal-combustion engine, based
on the reaction torque of the motor detected by the torque
detecting means.
Inventors: |
Takaoka; Toshifumi (Toyota,
JP), Hirose; Katsuhiko (Toyota, JP), Kanai;
Hiroshi (Toyota, JP), Inoue; Toshio (Toyota,
JP), Kusada; Masaki (Toyota, JP),
Nishigaki; Takahiro (Toyota, JP), Kojima;
Masakiyo (Toyota, JP), Yamaguchi; Katsuhiko
(Toyota, JP) |
Assignee: |
Toyota Jidosha Kabushiki Kaisha
(Toyota, JP)
|
Family
ID: |
27341751 |
Appl.
No.: |
09/868,865 |
Filed: |
June 21, 2001 |
PCT
Filed: |
September 17, 1999 |
PCT No.: |
PCT/JP99/05074 |
PCT
Pub. No.: |
WO00/39444 |
PCT
Pub. Date: |
July 06, 2000 |
Foreign Application Priority Data
|
|
|
|
|
Dec 24, 1998 [JP] |
|
|
10-367238 |
Dec 24, 1998 [JP] |
|
|
10-367253 |
Dec 24, 1998 [JP] |
|
|
10-367256 |
|
Current U.S.
Class: |
290/40C; 322/16;
180/65.235; 180/65.27; 180/65.28; 180/65.285 |
Current CPC
Class: |
B60W
10/06 (20130101); B60K 6/365 (20130101); F02D
19/0636 (20130101); F02D 29/06 (20130101); F02D
41/1497 (20130101); B60W 10/26 (20130101); F02D
41/0025 (20130101); B60K 6/445 (20130101); B60W
20/00 (20130101); B60W 20/10 (20130101); F02D
19/061 (20130101); B60W 10/08 (20130101); B60W
2710/0616 (20130101); Y02T 10/36 (20130101); B60W
2555/20 (20200201); B60K 1/02 (20130101); B60L
2240/443 (20130101); B60W 2510/0657 (20130101); B60W
2510/0676 (20130101); Y02T 10/30 (20130101); B60W
2510/083 (20130101); B60W 2530/213 (20200201); Y02T
10/642 (20130101); B60W 2710/0666 (20130101); B60W
2510/081 (20130101); B60L 2240/423 (20130101); B60W
2510/0638 (20130101); B60W 2710/0644 (20130101); B60L
2240/445 (20130101); Y02T 10/62 (20130101); F02D
2200/0612 (20130101); Y02T 10/6286 (20130101); B60L
2240/441 (20130101); B60L 2240/421 (20130101); Y02T
10/6239 (20130101); Y02T 10/64 (20130101) |
Current International
Class: |
B60K
6/00 (20060101); B60K 6/04 (20060101); F02D
41/14 (20060101); F02D 41/00 (20060101); F02D
29/06 (20060101); B60K 1/02 (20060101); B60K
1/00 (20060101); F02N 011/06 () |
Field of
Search: |
;290/4A,4C,4D ;318/8,9
;180/65.2 ;322/29,16 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
62-29745 |
|
Feb 1987 |
|
JP |
|
4-265447 |
|
Sep 1992 |
|
JP |
|
5-52707 |
|
Mar 1993 |
|
JP |
|
6-288289 |
|
Oct 1994 |
|
JP |
|
8-294205 |
|
Nov 1996 |
|
JP |
|
9-256898 |
|
Sep 1997 |
|
JP |
|
2712332 |
|
Oct 1997 |
|
JP |
|
9-268941 |
|
Oct 1997 |
|
JP |
|
9-303193 |
|
Nov 1997 |
|
JP |
|
9-308012 |
|
Nov 1997 |
|
JP |
|
10-110636 |
|
Apr 1998 |
|
JP |
|
WO 93/07019 |
|
Apr 1993 |
|
WO |
|
Primary Examiner: Ponomarenko; Nicholas
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
What is claimed is:
1. An output state detecting apparatus of internal-combustion
engine, comprising: an internal-combustion engine; a generator
driven by said internal-combustion engine to generate electric
power; torque detecting means for detecting a reaction torque of
said generator; and output state detecting means for detecting an
output state of said internal-combustion engine, wherein said
output state detecting means detects the output state of said
internal-combustion engine, based on the reaction torque of said
motor detected by said torque detecting means.
2. The output state detecting apparatus of internal-combustion
engine according to claim 1, wherein said internal-combustion
engine and said motor are connected through power dividing means,
and wherein a predetermined relation is met by a rotational speed
of said internal-combustion engine, a rotational speed of said
generator, an output torque of said internal-combustion engine, and
the reaction torque of said generator.
3. The output state detecting apparatus of internal-combustion
engine according to claim 1, wherein said output state detecting
means is combustion state determining means for determining a
combustion state of said internal-combustion engine.
4. The output state detecting apparatus of internal-combustion
engine according to claim 3, further comprising rotation detecting
means for detecting a rotational speed of said internal-combustion
engine, wherein said combustion state determining means references
said rotational speed of said internal-combustion engine on the
occasion of determining the combustion state of said
internal-combustion engine.
5. The output state detecting apparatus of internal-combustion
engine according to claim 3, further comprising: rotation control
means for controlling said generator to maintain a rotational speed
of said internal-combustion engine in a predetermined range; and
required torque calculating means for calculating a target of an
output torque of said internal-combustion engine, wherein said
combustion state determining means compares the target of the
output torque of said internal-combustion engine calculated by said
required torque calculating means with an output torque of said
internal-combustion engine calculated from the reaction torque
detected by said torque detecting means, thereby determining the
combustion state of said internal-combustion engine.
6. The output state detecting apparatus of internal-combustion
engine according to claim 3, further comprising: rotation control
means for controlling said generator to maintain a rotational speed
of said internal-combustion engine in a predetermined range; and
rotation detecting means for detecting the rotational speed of said
internal-combustion engine, wherein when said internal-combustion
engine is in a self-sustaining operation in which said rotation
control means is not controlling the rotational speed of said
internal-combustion engine, said combustion state detecting means
determines the combustion state of said internal-combustion engine,
based on the rotational speed of said internal-combustion engine
detected by said rotation detecting means.
7. The output state detecting apparatus of internal-combustion
engine according to claim 3, further comprising operational state
detecting means for detecting various information that can affect
the operational state of said internal-combustion engine, wherein
said combustion state determining means changes a threshold used in
the determination of the combustion state, according to the various
information detected by said operation condition detecting
means.
8. The output state detecting apparatus of internal-combustion
engine according to claim 7, wherein said various information
detected by said operational state detecting means is either of the
atmospheric pressure, a cooling water temperature of said
internal-combustion engine, an intake air flow, an engine speed, an
air-fuel ratio, ignition timing, fuel quality, and electric power
generated by said generator, or a combination thereof.
9. The output state detecting apparatus of internal-combustion
engine according to claim 3, further comprising rotation control
means for controlling a rotational speed of said generator to
maintain a rotational speed of said internal-combustion engine in a
predetermined range, wherein said combustion state determining
means halts the determination of the combustion state when a
control variable of said rotation control means is not less than a
predetermined threshold.
10. The output state detecting apparatus of internal-combustion
engine according to claim 9, wherein said rotation control means
controls the rotational speed of said generator by PID control, and
wherein said combustion state determining means determines that the
control variable of said rotation control means is not less than
the predetermined threshold, when a change amount of the component
P in said PID control is not less than a predetermined value.
11. The output state detecting apparatus of internal-combustion
engine according to claim 3, further comprising: rotation control
means for controlling said generator to maintain a rotational speed
of said internal-combustion engine in a predetermined range; and
rotational speed detecting means for detecting the rotational speed
of said internal-combustion engine, wherein said combustion state
detecting means halts the control carried out by said rotation
control means and determines the combustion state of said
internal-combustion engine, based on the rotational speed of said
internal-combustion engine detected in the halt state by said
rotation detecting means.
12. The output state detecting apparatus of internal-combustion
engine according to claim 3, wherein said internal-combustion
engine is a multiple-cylinder internal-combustion engine, said
output state detecting apparatus further comprising cylinder
discriminating means for discriminating a cylinder under execution
of a combustion stroke in said internal-combustion engine, wherein
said combustion state determining means determines a combustion
state of each cylinder from the reaction torque detected by said
torque detecting means and the cylinder under the execution of the
combustion stroke discriminated by said cylinder discriminating
means.
13. The output state detecting apparatus of internal-combustion
engine according to claim 12, further comprising combustion state
changing means for changing a combustion condition in a cylinder a
combustion state of which was determined as being instable by said
combustion state determining means, to control the combustion state
toward a stable combustion state.
14. The output state detecting apparatus of internal-combustion
engine according to claim 1, wherein said output state detecting
means is fuel quality determining means for determining fuel
quality of said internal-combustion engine.
15. The output state detecting apparatus of internal-combustion
engine according to claim 14, further comprising rotation control
means for controlling said generator to maintain an rotational
speed of said internal-combustion engine in a predetermined range,
wherein said fuel quality determining means determines the fuel
quality, based on a result of detection of said torque detecting
means during a period in which said rotation control means
maintains the rotational speed of said internal-combustion engine
in the predetermined range.
16. The output state detecting apparatus of internal-combustion
engine according to claim 14, wherein said fuel quality determining
means comprises first torque calculating means for calculating an
output torque of said internal-combustion engine, based on the
reaction torque detected by said torque detecting means, and second
torque calculating means for calculating an output torque of said
internal-combustion engine from an operational state of said
internal-combustion engine, wherein the fuel quality is determined
based on comparison between the output torques calculated by said
first torque calculating means and said second torque calculating
means.
17. The output state detecting apparatus of internal-combustion
engine according to claim 16, wherein said second torque
calculating means judges the operational state of said
internal-combustion engine and calculates the output torque of said
internal-combustion engine, based on at least one value of a
cooling water temperature, an intake air flow rate, an engine
rotational speed, an air-fuel ratio, and ignition timing.
18. The output state detecting apparatus of internal-combustion
engine according to claim 14, wherein said fuel quality determining
means determines the fuel quality, based on a result of detection
of said torque detecting means immediately after cold starting.
19. The output state detecting apparatus of internal-combustion
engine according to claim 16, wherein said fuel quality determining
means determines the fuel quality, based on a result of detection
of said torque detecting means immediately after cold starting.
20. The output state detecting apparatus of internal-combustion
engine according to claim 17, wherein said fuel quality determining
means determines the fuel quality, based
Description
TECHNICAL FIELD
The present invention relates to an apparatus for detecting output
state of internal-combustion engine.
BACKGROUND ART
Cars equipped with an engine and a motor-generator (functioning as
a motor or as a generator), e.g., so-called hybrid cars are
recently available for use. In such hybrid cars, in order to run
the engine in the efficient range of the engine revolutions, the
engine and the motor-generator are connected via a planetary gear
and the motor-generator is controlled to maintain the engine speed
(revolutions) at the efficient revolutions.
DISCLOSURE OF THE INVENTION
The inventors found that in the cars having the engine and the
motor-generator it was difficult to detect an output state of the
internal-combustion engine, based on the angular velocity of
rotation thereof, because the motor-generator was designed to
control the angular velocity of rotation of the output shaft of the
engine to a substantially constant level.
Accordingly, an object of the present invention is to provide
output state detecting apparatus that can detect an output state of
an internal-combustion engine, in vehicles and others having the
internal-combustion engine and the motor.
For example, there is the technique disclosed in Japanese Patent
Application Laid-Open No. H02-49955, as a device for detecting
misfiring (the output state of the internal-combustion engine) in
cylinders of the internal-combustion engine due to trouble in the
fuel valve and/or the ignition system. This technique is to detect
the angular velocity of rotation of the output shaft of the engine
and determine an abnormal cylinder suffering misfiring, based on
anomaly of angular velocity. However, since the engine speed is
controlled by the motor-generator in the cars having the engine and
the motor-generator as described above, it is hard to detect the
combustion state (output state), based on the engine speed, as in
this technique.
As another technique, the fuel quality is detected in order to run
the internal-combustion engine stably and reduce pollutant
components in exhaust gas emitted. Since the output of the
internal-combustion engine can vary depending upon change of the
fuel quality, the fuel quality can be regarded as one of output
states of the internal-combustion engine. For example, the device
described in Japanese Patent Application Laid-Open No. H09-256898
is known as a fuel quality detecting device. The fuel quality
detecting device described in No. H09-256898 is designed to
determine the fuel quality, based on change of the engine speed
during driving auxiliary accessory devices.
When the fuel quality is heavy and when the fuel attaches, for
example, to the internal wall of the intake pipe (intake port) upon
a cold start, the attaching fuel becomes resistant to evaporation.
Unless the fuel quality is detected and unless fuel injection
quantity is corrected based on the result of the detection, the
air-fuel ratio will tend to become lean. This will lead to instable
output and running states of the internal-combustion engine and/or
to increase in the amount of pollutant substances in the exhaust
gas.
However, since the engine speed is controlled by the
motor-generator in the cars having the engine and the
motor-generator (for driving of road wheels and for power
generation), variation of engine speed is very small and it is
considerably difficult to determine the fuel quality from the
variation of engine speed.
An output state detecting apparatus according to the present
invention comprises an internal-combustion engine, a generator
driven by the internal-combustion engine to generate electric
power, torque detecting means for detecting a reaction torque of
the generator, and output state detecting means for detecting an
output state of the internal-combustion engine, wherein the output
state detecting means detects the output state of the
internal-combustion engine, based on the reaction torque of the
motor detected by the torque detecting means.
Since the motor generates electric power while receiving the output
of the internal-combustion engine, the reaction torque of the motor
reflects the output of the internal-combustion engine. Therefore,
the present invention permits the detection of the output state of
the internal-combustion engine based on the reaction torque of the
motor.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram of main part of a hybrid car
equipped with an output state detecting apparatus of
internal-combustion engine according to the present invention.
FIG. 2 is a schematic, structural diagram of a dividing mechanism
in the apparatus of FIG. 1.
FIG. 3 is an alignment chart to show the relation among rotational
speeds of components in the power dividing mechanism of FIG. 2.
FIG. 4 is a flowchart to show combustion state detecting operation
of the output state detecting apparatus of internal-combustion
engine according to the present invention.
FIG. 5 is a flowchart to show combustion state detecting operation
of the output state detecting apparatus of internal-combustion
engine according to the present invention.
FIG. 6 is a graph to show temporal variation of engine torque.
FIG. 7 is a flowchart to show fuel quality detecting operation (in
a steady state of the engine) the output state detecting apparatus
of internal-combustion engine according to the present
invention.
FIG. 8 is a flowchart to show computation processing of fuel
injection quantity TAU upon starting.
FIG. 9 is a flowchart to show computation processing of fuel
injection quantity TAU after starting.
FIG. 10 is a flowchart to show a calculation routine of warm-up and
high-load correction factor FWLOTP.
FIG. 11 is a flowchart to show a calculation routine of increase
correction factor FASE after starting.
FIG. 12 is a flowchart to show a calculation routine of air-fuel
ratio feedback correction factor FAF.
FIG. 13 is a timing chart to show changes of output A/F from an
air-fuel ratio sensor, delay counter CDLY, air-fuel ratio flag F1,
and air-fuel ratio feedback correction factor FAF.
FIG. 14 is a flowchart to show a calculation routine of
wall-attaching fuel correction factor FMW.
FIG. 15 is a flowchart to show fuel quality detecting operation (in
a transient state of the engine) of the output state detecting
apparatus of internal-combustion engine according to the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described hereinafter in more detail
with reference to the accompanying drawings. FIG. 1 shows the
structure of a car having an output state detecting apparatus of
the present invention.
This car is a so-called hybrid car having an engine 1 being an
internal-combustion engine, and a motor-generator (MG) 2, as its
power sources. This car also has a motor-generator (MG) 3 for
generating electric power while receiving output of the engine 1.
These engine 1, MG 2, and MG 3 are connected to each other by a
power divider 4. The power divider 4 divides the output of the
engine 1 between MG 3 and drive wheels 5. The power divider 4 also
has the function of transmitting output from MG 2 to the drive
wheels 5 and the function as a transmission (gear ratio changer) of
drive force which is transmitted via reduction unit 7 and drive
shaft 6 to the drive wheels 5. The power divider 4 will be detailed
later.
MG 2 is an AC(alternating-current) synchronous motor and is driven
by AC power. An inverter 9 converts electric power charged in
battery 8 from DC to AC to supply AC power to MG 2, and also
converts the electric power generated by MG 3 from AC to DC to
charge it in the battery 8. Basically, MG 3 also has the structure
almost identical to the structure of MG 2 and thus has the
structure as an AC synchronous motor. MG 2 mainly functions to
output the drive power, while MG 3 mainly functions to generate the
electric power while receiving the output of the engine 1.
Although MG 2 mainly functions to generate the drive power, it can
also generate electric power (regenerative power generation) by
making use of rotation of the drive wheels 5 and thus can also
function as a generator. At this time, the brake (regenerative
brake) is applied to the drive wheels 5 and thus it can be used in
combination with the foot brake (oil brake) and engine brake to
stop the car. On the other hand, MG 3 mainly functions to generate
the electric power while receiving the output of the engine 1, but
can also function as an electric motor that receives the power from
the battery 8 through the inverter 9 to drive.
The crankshaft 15 of engine 1 is equipped with a crank position
sensor 21 for detecting the piston positions and the rotational
speed of engine 1. The crank position sensor 21 is connected to
engine ECU 11. On each of drive shafts of MG 2 and MG 3, a rotation
sensor (resolver) 22, 23 is mounted to detect the rotational
position and speed of each MG. The rotation sensors 22, 23 are
connected each to motor ECU 12.
The power divider 4 described above is shown together with the
engine 1, MG 2, and MG 3 in FIG. 2. Since the power divider 4
herein is comprised of a planetary gear unit, the power divider 4
will also be called hereinafter planetary gear unit 4. The
planetary gear unit 4 is composed of a sun gear 4a, planetary gears
4b disposed around this sun gear 4a, a ring gear 4c disposed
further outside the planetary gears 4b, and a gear carrier 4d
holding the planetary gears 4b.
Here the crankshaft 15 of engine 1 is coupled through damper 16 to
a center shaft 17 and this center shaft 17 is coupled to the gear
carrier 4d. Namely, the output of engine 1 enters the gear carrier
4d of the planetary gear unit 4. MG 2 has a stator 2a and a rotor
2b inside and this rotor 2b is coupled to the ring gear 4c. The
rotor 2b and ring gear 4c are further coupled to a first gear 7a of
the reduction unit 7.
The reduction unit 7 consists of first gear 7a, torque transfer
chain 7b, second gear 7c, third gear 7d, and final gear 7e. Namely,
the output of motor 2 is supplied to the ring gear 4c of the
planetary gear unit 4 and is transmitted through the reduction unit
7 and differential gear 18 to the drive shaft 6. Consequently, MG 2
is always connected to the axle shaft 6.
MG 3, similar to MG 2, has a stator 3a and a rotor 3b inside, and
this rotor 3b is coupled to the sun gear 4a. Namely, the output of
engine 1 is divided by this planetary gear unit 4 to be supplied
through the sun gear 4a to the rotor 3b of MG 3. The output of
engine 1 is divided by this planetary gear unit 4 to be able to be
transmitted through the ring gear 4c etc. to the drive shaft 6,
too.
Here the whole of planetary gear unit 4 can be used as a
continuously-variable transmission by controlling the rotation of
the sun gear 4a, based on control of power generated by MG 3.
Namely, the output of engine 1 or (and) MG 2 is first subjected to
speed conversion in the planetary gear unit 4 and is then supplied
to the drive shaft 6. It is also feasible to control the engine
speed of the engine 1 by controlling the power generated by MG 3
(or power consumption when MG3 functions as a motor). In this
example, control is made to maintain the rotational speed of engine
1 in the range of good energy efficiency.
FIG. 3 is an alignment chart to show a balance among rotational
speeds and directions of the respective gears in the planetary gear
unit 4 (i.e., rotational speeds and directions of the engine 1, MG
2, and MG 3 connected to the respective gears). Here the vertical
axis represents the rotational speeds of the respective gears (sun
gear 4a, ring gear 4c, and gear carrier 4d), i.e., the rotational
speeds of the engine 1, MG 2, and MG 3. On the other hand, the
horizontal axis represents the gear ratio of the gears. Where a
ratio of the number of teeth of the sun gear 4a to the number of
teeth of the ring gear 4c is .rho., the axis corresponding to the
gear carrier 4d in FIG. 3 is located at a coordinate position
obtained by internal division between the axes of the sun gear 4a
and the ring gear 4c at the ratio of 1:.rho.. Then the following
relation is met by the rotational speed Ne of the engine 1 and the
gear carrier 4d, the rotational speed Nm of MG 2 and the ring gear
4c, and the rotational speed Ng of MG 3 and the sun gear 4a.
##EQU1##
During a standstill of the engine 1 in a car stop state MG 2 and MG
3 are also at a standstill and are thus in the state indicated by a
line A in FIG. 3. During a starting period or during a low speed
cruise, the property of MG 2 capable of generating high torque in a
low rotation condition is utilized and the engine 1 is kept at a
standstill, whereby only MG 2 is operated by the power from the
battery 8 to drive the car (line B). In the hybrid cars,
immediately after the starter key is turned on, the engine 1 is
activated for a certain period even in the car stop condition for
the purpose of warm-up of catalyst. During the engine start period
in this car stop condition MG 2 is at a standstill and MG 3 is used
as a starter to activate the engine 1, thereby implementing the
engine starting (line C).
During a constant speed cruise the power of engine 1 is mainly
utilized to drive the car, MG 3 is little rotated (it generates
almost no power), and MG 2 is activated if necessary to assist the
driving force (line D). During a high-load cruise, e.g., during
acceleration from the constant speed cruise, the speed of engine 1
is increased and MG 3 generates power to increase the assist force
of MG 2, thereby implementing operation making use of the driving
forces of the engine 1 and MG 2 (line E). During a braking period
and during deceleration MG 2 generates regenerative power with
converting kinetic energy into electric power. On such occasions
that the charge of the battery 8 is low, the engine 1 is activated
even during a low-load cruise whereby MG 3 generates electric power
by utilizing the output of engine 1, thereby charging the battery 8
through the inverter 9.
The control of rotational speeds of MG 2, MG 3 is implemented in
such a way that the motor ECU 12 controls the inverter 9 with
reference to the output of the rotation sensors 22, 23. This also
permits control of the rotational speed of the engine 1.
These control operations are performed by some electronic control
units (ECUs) (see FIG. 1). The drive by the engine 1 and the
electric drive by MG 2 and MG 3, characteristic of the hybrid car,
are generally controlled by the main ECU 10. The main ECU 10 makes
a balance between the drive by the engine 1 and the electric drive
by MG 2 and MG 3 so as to optimize energy efficiency and issues
each control command to control the engine 1, MG 2, and MG 3, to
the engine ECU 11 and to the motor ECU 12.
The engine ECU 11 and motor ECU 12 also transmit information on the
engine 1, MG 2, and MG 3 to the main ECU 10. Also connected to the
main ECU 10 are a battery ECU 13 for controlling the battery 8 and
a brake ECU 14 for controlling the brakes. The battery ECU 13
monitors the charge condition of the battery 8, and if the charge
becomes short it will issue a charge request command to the main
ECU 10. Receiving the charge request, the main ECU 10 performs
control of making the generator 3 generate electric power to charge
the battery 8. The brake ECU 14 takes charge of braking of the car
and, together with the main ECU 10, controls the regenerative brake
by MG 2.
When neither of the output torque Te of the engine 1, the output
torque Tm of MG 2, and the reaction torque Tg by power generation
of MG 3 is null and when they are in balance (in a steady state),
the following relations are met. ##EQU2##
The reaction torque described above is a reaction caused by MG 3
during power generation. Since Tg normally acts in the reverse
direction to Te and Tm, it takes negative values.
When the three torques are out of balance on the other hand, the
rotational speed of each component varies according to a difference
from torque in a balanced state. At this time, where .omega.e
represents the angular velocity of rotation of the engine 1,
.omega.g the angular velocity of rotation of MG 3, and Ie and Ig
their moments of inertia including gears, the following equation
holds. ##EQU3##
For the moments of inertia Ie, Ig numerical values thereof are
preliminarily obtained by experiments and stored in ROM in the main
ECU 10, and the values are taken out of the ROM to be used. The
angular velocity .omega.e of rotation of the engine 1 is detected
by the crank position sensor 21. The angular velocity .omega.g of
rotation of MG 3 is detected by the rotation sensor 23.
The output state detecting operation of the engine 1 in the hybrid
car of the structure described above will be described below. First
described is a case of detecting a combustion state as an output
state of the internal-combustion engine. FIG. 4 is a flowchart of
this combustion state detecting operation. The processing based on
this flowchart is carried out only during operation of the engine
1.
In step S11 it is first determined whether the engine was started
immediately before the present time. When the present time is
within a predetermined period from the start, the flow transfers to
step S12 to determine whether a fixed time has elapsed since a rise
of the engine speed Ne. The reason is that during the period before
a sufficient rise of the engine speed Ne or during a short period
after the rise, warming-up is under way or MG 3 is working as a
starter to rotate the engine 1, and combustion in the engine 1 is
not stable yet, thus requiring no judgment on misfiring. Therefore,
before a lapse of the fixed time, the processing thereafter is
skipped to end the operation.
After a lapse of the fixed time, the flow moves to step S13 to
compare the detected reaction torque Tg of MG 3 with balanced
reaction torque Tgreq. The balanced reaction torque Tgreq is a
reaction torque that, in such an operating state of the engine 1 as
to output an engine required torque Tereq requested of the engine
1, is generated by MG 3 in a balanced state with the required
torque Tereq. This will be detailed below.
The main ECU 10 calculates the respective required torques Tereq,
Tmreq of the engine 1 and MG 2 with reference to vehicle speed,
battery capacity, auxiliary output, etc. at that point, based on
driver's operation on the accelerator pedal. Further, the ECU
determines the respective rotational speeds Ne, Nm of the engine 1
and MG 2 to meet these required torques Tereq, Tmreq. At this time
the ECU also determines the rotational speed Ng of MG 3 from Eq
(1). Then the main ECU 10 controls the motor ECU 12 to control
amplitudes and frequencies of electric currents flowing through the
inverter 9 to MG 2, MG 3, thereby regulating the rotational speeds
Nm, Ng of MG 2, MG 3. By this control the rotational speed of the
engine 1 can also be adjusted to a predetermined rotational
speed.
At this time, if the combustion state of the engine 1 is stable,
the actual output torque Te of the engine 1 will agree with the
required torque Tereq. However, if the combustion state of the
engine 1 is unstable with misfiring or the like, the actual output
torque Te will become lower than the required torque Tereq. At this
time, an absolute value of the reaction torque Tg of MG 3 becomes
smaller than an absolute value of the balanced torque Tgreq with
the required torque Tereq of the engine 1.
Accordingly, whether a judgment on misfiring is feasible or not is
judged by comparison between them. The reaction torque Tg can be
calculated from the rotational speed of MG 3 measured by the
rotation sensor 23 and the electric power generated by MG 3.
Alternatively, MG 3 may be provided with a torque sensor. When the
absolute value of the reaction torque Tg calculated from the
rotational speed of MG3 and the generated power by MG 3 is smaller
than the absolute value of the balanced reaction torque Tgreq in
balance with the required torque Tereq of the engine 1, the flow
moves to step S19 to determine that misfiring occurred; otherwise,
the processing thereafter is skipped to end the operation.
If a sufficient time has elapsed since the start of the engine 1,
the flow transfers to step S14 to determine whether the engine is
under self-sustaining operation. Here the self-sustaining operation
of the engine is a state in which the rotational speed of the
engine 1 is not controlled by MG 3, and the speed of engine 1 is
controlled by the engine ECU 11 as in the case of the engines
mounted on common cars. Since the processing in the following steps
S15 to S17 is specific processing carried out during the control of
rotational speed of engine 1 by MG 3, these procedures are skipped
during the self-sustaining operation of the engine to jump the step
S18.
When the engine 1 is not under the self-sustaining operation, the
flow moves to step S15. In step S15, a judgment is made on a
controlled variable in the control of the rotational speed of MG 3.
For example, in use of PID control, a judgment is made on a change
of controlled variable of the component P. When the controlled
variable of the component P exhibits a rapid change, the status is
that a rapid change is also made in the rotational speed of MG 3
and, in turn, in the rotational speed and output torque of the
engine 1 per se. When the controlled variable of the component P
demonstrates a rapid change, variation is great in the rotational
speed of MG 3 (i.e., in the rotational speed and output torque of
the engine 1). For this reason, regardless of presence/absence of
misfiring, the variation cannot be used for the judgment on
misfiring. Accordingly, when the controlled variable exhibits a
rapid change, the processing thereafter is skipped. The misfire
judgment is not done. When the change of the controlled variable is
small, the flow transfers to step S16.
In step S16 the reaction torque Tg is compared with a threshold
Tgx. With occurrence of misfiring, as described previously, the
absolute value of the output torque Te of the engine 1 becomes
smaller and the absolute value of the reaction torque Tg of MG 3
also becomes smaller. Therefore, when the absolute value of the
reaction torque Tg is smaller than the absolute value of the
threshold Tgx, it is determined that the possibility of misfiring
is high and the flow goes to step S17; otherwise, it is determined
that the combustion state is stable, and the processing thereafter
is skipped. Here the threshold Tgx can be calculated based on Eq
(3) if the rotational speeds of the engine 1 and MG 3 are stable
(in a steady state) or based on Eq (4) if the rotational speeds of
the engine 1 and MG 3 are changing (in a transient state).
When step S16 ends in yes with the judgment of the high possibility
of misfiring, the rotational speed of the engine 1 is referenced in
step S17 and step S18 in order to make a better judgment on
presence/absence of misfiring. At this stage, the engine 1 is not
in the self-sustaining operation and the rotational speed thereof
is controlled by MG 3. Thus the engine 1 is in a state in which
variation of rotation is small due to misfiring. For this reason,
in step S17 the threshold for the rotation variation used in the
judgment in next step S18 is set to a value lower than the
threshold during the self-sustaining operation of the engine.
Next, the processing in step 18 is carried out as follows. First,
in step S18 after yes of step S14, it is determined whether the
rotation variation is not less than the threshold of rotation
variation for the self-sustaining operation of the engine 1. When
the rotation variation is not less than the threshold, the flow
moves to step S19 to make a judgment of misfiring.
On the other hand, in step S18 after yes of step S16 and after the
change of the rotation variation threshold in step S17, it is
determined whether the rotation variation is not less than the
rotation variation threshold for the engine 1 not being in the
self-sustaining operation. When the rotation variation is not less
than the threshold, the flow transfers to step S19 to make a
judgment of misfiring. If the frequency of occurrence of misfiring
is high in comparison with the number of cycles of the engine 1,
the main ECU 10 displays the fact in a meter display system and
terminates the processing.
The determination process of step S16 may be replaced by a
determination process similar to step S13. Since the determination
process of step S13 is to make a judgment based on the required
torque Tereq of the engine 1, it has the advantage of capability of
making stable determination from immediately after the start of
engine 1.
The above operation is arranged to determine in step S14 whether
the engine 1 is now under the self-sustaining operation, but the
operation may be modified so that the engine 1 is forced into the
self-sustaining operation at every predetermined time or in a cycle
after detection of misfiring. In these cases, since the control of
the rotational speed of the engine 1 by MG 3 is terminated, the
misfiring of the engine 1 can be detected based on only the
variation in rotation.
During the control of rotation of the engine 1 by MG 3, the
judgment on misfiring may be made, not using the rotation variation
of the engine 1, but using only the detection of the torque
variation in step S16 or in step S13. When instable combustion,
though not leading to complete misfiring, occurs continuously,
shortage of torque appears noticeable whereas the variation in the
speed of engine 1 is small. Such continuous instable combustion can
be detected by detecting the variation in torque.
The apparatus may be configured to store in the main ECU 10 a map
of thresholds Tgx of reaction torque according to rotational speeds
Ne of the engine 1 and rotational speeds Ng of MG 3 during constant
speed cruises and perform the determination process of step S16
using this map. Likewise, the apparatus may be arranged to correct
these values of the map during acceleration/deceleration to obtain
the threshold Tgx and carry out the determination process based
thereon.
When the engine 1 is not in the self-sustaining operation, the
rotation variation of the engine 1 is relieved by the control by MG
3. Therefore, if the same threshold of rotation variation as that
in the self-sustaining operation were used, a judgment could not be
made even with occurrence of misfiring. In the present invention,
the threshold for the judgment on the rotation variation of the
engine 1 is lowered in that case whereby an accurate judgment can
be made even under the relieved condition. Since the rotation
variation of engine 1 responds quicker to occurrence of misfiring
than the torque variation, the accuracy is higher for detection of
a single misfire. Accordingly, it is preferable to use the both,
but only either one of them may also be used for the judgment on
misfiring.
The various thresholds, e.g. Tgx, Tgreq, the threshold for rotation
variation, etc., vary depending upon the atmospheric pressure,
cooling water temperature of the internal-combustion engine, intake
air flow, engine speed, air-fuel ratio, ignition timing, fuel
quality, electric power generated by the generator or output of the
generator, and so on. It is thus preferable to change the
thresholds, using one or a combination of these as a parameter.
This makes it feasible to make the accurate misfiring
determination, regardless of the operational status. When the power
divider such as the planetary gear 4 as described above is
employed, a power division state of the power divider may also be
added to the above parameters.
The atmospheric pressure is detected by an atmospheric pressure
sensor 24. The cooling water temperature is detected by a cooling
water temperature sensor 25 mounted on the engine 1. The intake air
flow is detected from the pressure in the intake pipe, which is
detected by a pressure sensor 27 mounted on the intake pipe 30.
Alternatively, the intake air flow may be detected by an air flow
meter mounted on the intake pipe 30 of the engine 1. The engine
speed is detected by the crank position sensor 21. The air-fuel
ratio is detected by an air-fuel ratio sensor 26 provided on the
exhaust pipe 31 of the engine 1.
Since ignition of ignition plugs 29 of the engine 1 is implemented
by sending ignition signals from the engine ECU 11 to ignition
coils 28, the ignition timing can be detected by the ECU 11, based
on the output of the crank position sensor 21. The detection of the
fuel quality will be detailed later. The generated electric power
or output of MG 3 is detected by the motor ECU 12. The power
division state can be detected by the engine ECU 11 controlling the
driving state of the planetary gear unit 4.
As described above, the output torque Te of the engine 1 can be
calculated from the reaction torque Tg of MG 3, by making use of
the predetermined relations such as Eqs (3), (4) between the output
torque Te of the engine 1 and the reaction torque Tg of MG 3. If
there occurs a change in the combustion state due to misfiring or
the like, the output torque Te of the engine 1 will vary.
Therefore, the combustion state can be determined from the change
in the output torque Te of the engine 1 and the combustion state
can be eventually determined from the reaction torque Tg of MG
3.
The change in the combustion state leads to change in the speed of
the engine 1. When the combustion state varies from the normal
combustion state, the output torque Te of the engine 1 differs even
at the same rotational speed. Accordingly, the determination can be
made more accurately by also using the speed of the engine 1 for
the determination of the combustion state.
Since the output torque Te of the engine 1 varies according to the
speed of the engine 1, the control over the output torque Te of the
engine 1 can be performed by controlling the speed of the engine 1.
A target value (required torque Tereq) of the output torque Te on
the engine 1 side at this time can be calculated from the
controlled speed. Then the actual output torque Te of the engine 1
can be calculated from the reaction torque Tg of MG 3 as described
previously. In the normal combustion state the actual output torque
Te agrees with the required torque Tereq, but with occurrence of
abnormal combustion the actual output torque Te will become smaller
than the required torque Tereq. For this reason, it is feasible to
determine the combustion state by comparing the two torques.
In the self-sustaining state of the engine 1 the rotation of the
engine 1 is free of control from the outside of the engine.
Therefore, change in the combustion state of the engine 1 results
in variation in the speed of the engine 1, and it thus becomes
feasible to determine the combustion state from only the variation
in the speed of the engine 1.
If there is a difference in the various parameters affecting the
operational state of the engine 1, e.g., in the atmospheric
pressure, cooling water temperature of engine 1, intake air flow,
engine speed, air-fuel ratio, ignition timing, fuel quality,
electric power generated by MG 3, output of MG 3, etc., the output
torque yielded will differ even at the same rotational speed. Since
tolerances also vary for stability of combustion, it becomes
feasible to finely adapt for the difference of the operational
state, by changing the various thresholds such as Tgx, Tgreq, the
threshold for rotation variation, etc. upon the determination.
When a controlled variable in the speed control of the engine 1 is
not less than a predetermined level, a deviation of the speed Ng of
MG 3 is great from the target speed. In this case, a rapid change
is seen in the speed Ng of MG 3 and, in turn, in the speed Ne of
the engine 1 with execution of control. Then the output torque Te
of the engine 1 also exhibits a rapid change therewith.
Accordingly, where the determination of the combustion state is
made by use of either the speed change or the torque change, it is
difficult to accurately detect the change of the combustion state
because of the great change in the speed or the torque with the
control. Therefore, it is preferable to halt the determination of
the combustion state.
While the speed Ng of MG 3 is under the PID control, a large change
in the component P means a large deviation of the rotational speed
Ng of MG 3 from the target speed. Since the change of the component
P can be detected relatively easily, it is preferable in the case
of the large change of the component P during the PID control, to
assume that the controlled variable in the control of speed of the
engine 1 as described above is not less than the predetermined
value.
When the control of the speed of the engine 1 by the control of
rotation of MG 3 is halted, variation appears in the speed of the
engine 1 according to the variation in the combustion state of the
engine 1. Accordingly, during the halt of the control over the
speed of engine 1 by MG 3, it is feasible to determine the
variation in the combustion state from this variation in the speed
of the engine 1.
Next described is a case of detecting the combustion state of each
cylinder as an output state of the internal-combustion engine. FIG.
5 is a flowchart of this combustion control operation. The
processing based on this flowchart is carried out only during the
operation of the engine 1.
First step S21 is a step of detecting the reaction torque Tg and a
cylinder in the combustion stroke. Here the reaction torque Tg can
be calculated from the speed of MG 3 measured by the rotation
sensor and the electric power generated by MG 3, by the motor ECU
12, as described above. optionally, a torque sensor may be mounted
on MG 3. The engine ECU 11 can determine the cylinder in the
combustion stroke, based on the output of the crank position sensor
21. In step S22 the engine torque Te is then calculated from the
reaction torque Tg according to Eq (3) during the steady operation
(in the steady state) or according to Eq (4) during variation in
the speed of engine 1 (in the transient state).
In subsequent step S23, the actual output torque Te of the engine 1
is compared with the required torque Tereq of the engine 1. The
control of the speed of the engine 1 at this time is just the same
as described in step S13 in the above-stated case illustrated in
FIG. 4. In addition to the control of the speed of the engine 1,
the engine ECU 11 also controls a fuel supply so as to realize a
predetermined air-fuel ratio in accordance with the required torque
Tereq and the engine speed Ne. However, if combustion conditions
are different, e.g., if there are variations of fuel supply among
the cylinders, there will appear a difference among torques
generated in the respective cylinders and this will eventually
result in variation in the engine torque.
FIG. 6 shows a temporal change curve of the output torque Te of the
engine 1 in a state wherein only the first cylinder in the
four-cylinder type engine 1 experiences rich combustion in the
steady state. The output torque Te of the engine 1 with the
rich-combustion cylinder being in the combustion stroke is larger
than those with the other cylinders being in the combustion stroke,
i.e., than the required torque Tereq. When lean combustion occurs
on the other hand, the output torque Te becomes smaller.
Accordingly, it is feasible to determine the combustion state by
comparing the required torque Tereq with the actual output torque
Te.
When in step S24 it is determined from the comparison result that a
certain cylinder is under rich combustion, an fuel injection
quantity correction factor of a corresponding fuel injector is
reduced so as to decrease the quantity of fuel introduced into the
cylinder of interest. When it is determined on the other hand that
a certain cylinder is under lean combustion, the fuel injection
quantity correction factor of a corresponding fuel injector is
increased so as to increase the quantity of fuel introduced into
the cylinder of interest. The correction factor may be changed in
proportion to the torque difference or stepwise.
By controlling fuel supplies to the respective cylinders so as to
decrease the torque variation, the variations are nullified in
air-fuel ratios among the cylinders and improvement is made in
exhaust emissions, because all the cylinders can be operated in the
stoichiometric region.
Described above was the case wherein the actual output torque Te of
the engine 1 was estimated from the reaction torque Tg of MG 3 and
the control was carried out based on the comparison between this
output torque Te and the required torque Tereq. Particularly, since
the reaction torque Tg must be constant during the steady operation
in which there is no change in the accelerator pedal position,
engine speed, and intake air flow, the apparatus may be arranged to
determine a cylinder whose reaction torque Tg in the combustion
stroke deviates from an average of those in the combustion stroke
of the other cylinders and to change the fuel injection quantity
correction factor for that cylinder. A change amount of the
correction factor at this time can be determined according to the
deviation. Further, during the operation with change in the
accelerator pedal position, engine speed, and intake air flow, the
deviation can also be estimated by referencing reaction torques Tg
in the combustion stroke of previous and subsequent combustion
cylinders.
The above mainly described the control to adjust the fuel injection
quantity, but it is also possible to adjust the intake air flow or
to adjust the air-fuel ratio itself by combination of the two
parameters. As another example, it is also feasible to control the
combustion state cylinder by cylinder, by controlling the fuel
injection timing and/or the ignition timing.
In addition to the above, when the car is equipped with an exhaust
gas recirculation (EGR) system for recirculating part of exhaust
gas to the air intake side, as an example of the combustion
condition to be controlled, quantity of recirculated gas may be
controlled. When the engine 1 is a lean-burn internal-combustion
engine such as a direct injection engine or the like, intake air
patterns such as swirling, tumbling, or the like may be controlled.
When the engine is an internal-combustion engine equipped with a
variable valve timing mechanism, the valve timing may be
changed.
As described above, the output torque Te of the engine 1 can be
calculated from the reaction torque Tg of MG 3, by making use of
the predetermined relations such as Eqs (3), (4) between the output
torque of the engine 1 and the reaction torque Tg of MG 3. When the
combustion state changes because of misfiring, rich combustion, or
the like, the output torque Te of the engine 1 varies. The output
torque Te of each cylinder takes a peak value in the combustion
stroke. Therefore, the combustion state of each cylinder can be
determined from the output torque Te in the combustion stroke.
Since this output torque Te can be calculated from the reaction
torque Tg of MG 3, it eventually becomes feasible to determine the
combustion state of each cylinder from the reaction torque Tg of MG
3 and the cylinder in the combustion stroke.
The control described above makes it feasible to control the
combustion state toward a stable state by determining the
combustion state of each cylinder and thereafter adjusting the
combustion conditions in a cylinder judged as being in an instable
combustion state, e.g., by adjusting the air-fuel ratio, fuel
injection quantity, fuel injection timing, ignition timing, or
intake air flow. This suppresses the torque variation caused by
dispersion of combustion states among the cylinders.
Next described is a case of detecting the fuel quality as an output
state of the internal-combustion engine. A flowchart of fuel
quality determining processing is provided in FIG. 7. The process
of determining the fuel quality will be described below along FIG.
7.
First, it is determined whether the engine 1 is in operation (step
100). The "in operation of engine" stated herein means "under
combustion of engine" except during the halt of engine and during
cranking. When the engine 1 is in operation, it is then determined
whether the engine is in a fuel cut period (step 101). Since during
the fuel cut period the fuel to be inspected is not burnt, it is
impossible to determine the fuel quality, as a matter of
course.
Unless the engine is in a fuel cut period, it is determined whether
a condition for execution of engine rotation control is met (step
102). The condition for execution of rotation control is,
specifically, that no control is effected over quantity of power
generation or discharge of MG 3, that a request for self-sustaining
operation (e.g., a request for activation of air conditioner or a
request for a rise of cooling water temperature of engine) is not
made to the engine 1, or that the vehicle speed of the hybrid car
is higher than a predetermined vehicle speed. If the rotation
control execution condition is met, the control of engine rotation
is executed in order to maintain the speed of engine 1 in a
predetermined region (step 103).
It is then determined whether a condition for determination of fuel
quality is met (step 104). The condition for determination of fuel
quality herein is whether the engine is in a warm-up mode
immediately after cold starting. If the fuel quality determination
condition is met, the reaction torque Tg of MG 3 is detected (step
105). The reaction torque Tg of MG 3 is calculated from electric
power generated, which is read through the inverter 9 and via the
motor ECU 12 into the main ECU 10 from the electric power generated
by MG 3 (or power consumption when MG 3 is working as a motor), and
from the rotational speed of MG 3 detected by the rotation sensor
23.
Then the output torque Te of the engine 1 is calculated using
aforementioned Eq (3), from the reaction torque Tg of MG 3 (step
106). Further, the operational state of the engine 1 is also judged
based on at least one of the cooling water temperature, intake air
flow, engine speed, air-fuel ratio, and ignition timing (or a
combination of these), and the output torque Te-cal of the engine 1
is also calculated from this operational state (step 107).
Although the output torque Te-cal was calculated from the
operational state of the engine 1 herein, it is also possible to
perform control using a fixed value equivalent to the output torque
Te-cal, as a torque criterion.
Then a difference is calculated between the output torque Te-cal
calculated based on the operational state of the engine 1 and the
output torque Te of the engine 1 calculated based on the reaction
torque Tg of MG 3, and it is determined whether the difference is
greater than a set reference preliminarily set (step 108).
When the difference between output torque Te-cal and output torque
Te is larger than the set reference, the fuel quality is heavy and
thus it can be determined that the actual output torque Te
calculated from the reaction torque Tg of MG 3 is lower than the
output torque Te-cal estimated from the operational state of the
engine 1. When the fuel is judged as being heavy, a fuel quality
index FQIND is set to 1 and stored in a backup RAM in the main ECU
10 (step 109).
On the other hand, when the difference between the output torque
Te-cal calculated based on the operational state of the engine 1
and the output torque Te of the engine 1 calculated based on the
reaction torque Tg of MG 3 is smaller than the set reference, the
fuel is not considered to be heavy and thus the fuel quality index
FQIND is set to 0 and stored in the backup RAM in the main ECU 10
(step 110). The fuel quality thus determined is reflected in the
operation of the engine 1 hereinafter.
During the determination of the fuel quality, the aforementioned
ECUs 10 to 12, together with the other various sensors and various
devices, also function as torque detecting means and fuel quality
determining means (first torque detecting means and second torque
detecting means). The torque detecting means is a means for
detecting the reaction torque Tg of MG 3 from its generating power
(or its dissipating power when MG 3 is working as a motor) and the
rotational speed thereof. The fuel quality determining means is a
means for determining the fuel quality (whether the fuel is heavy
or not), based on the reaction torque Tg of MG 3 detected. The fuel
quality determining means has the first torque detecting means and
the second torque detecting means. The first torque detecting means
is a means for calculating the output torque Te of the engine 1,
based on the reaction torque Tg of MG 3 detected, and the second
torque detecting means a means for calculating the output torque
Te-cal of the engine 1 from the operational state of the engine
1.
Since the output torque Te of the engine 1 varies depending upon
the fuel quality, the fuel quality (whether the fuel is heavy or
not) can be determined based on the reaction torque Tg of MG 3. The
fuel quality is detected immediately after cold starting herein.
The reason is that immediately after the cold starting, differences
in attaching amount of fuel on the internal wall of the intake pipe
and in evaporating amount of fuel become noticeable depending upon
the fuel quality and the change of the output torque of the engine
1 becomes larger because of the difference of the fuel quality,
thus facilitating the detection of the change of the output torque.
Since it is easier to detect the change of output torque of the
engine 1, the fuel quality can be determined more accurately. After
the engine 1 becomes fully warm, the temperature of the engine 1 is
also sufficiently high and there appears no big difference in the
evaporating amount of fuel. For this reason, the fuel quality is
detected better immediately after the cold starting.
The processing herein is configured to perform the control to
maintain the speed of the engine 1 positively in the predetermined
region, as described above. In this configuration, the change of
the output torque of the engine 1 can also be estimated through the
reaction torque Tg of MG 3 and the fuel quality can be detected
accurately.
In order to maintain the speed of the engine 1 in the predetermined
region, it is also possible to additionally use control of throttle
aperture to control the intake air flow to the engine 1. However,
when the reaction torque Tg of MG 3 is used in order to maintain
the speed of the engine 1 in the predetermined region, the
difference of the fuel quality is reflected in the reaction torque
Tg of MG 3 and thus the fuel quality can be determined more
accurately. If the fuel quality is intended to be determined from
only the speed of the engine 1, execution of the control to
maintain the speed in the predetermined region will lead to no
change (or very small change) in the rotational speed and thus the
determination of the fuel quality will become very difficult.
As described above, the fuel quality is first determined in the
steady state immediately after cold starting herein. If the hybrid
car is constructed so that when the ignition system is first
switched on, the warm-up mode is carried out to operate the engine
1 for a fixed period for warming-up of the engine 1, exhaust-gas
cleaning catalyst, etc. and establish the steady state in this
warm-up mode, the fuel quality can be determined during this
period. The reason why the warming-up of the exhaust-gas cleaning
catalyst is carried out is that the common exhaust-gas cleaning
catalysts do not exhibit the cleaning function below their
activation temperature and thus the warning-up is carried out to
increase the temperature of the catalyst to over this activation
temperature.
In another case, where a charge request to the battery 8 is present
immediately after cold starting, the engine 1 is activated to
generate electric power by the generator 3, and the fuel quality
can be determined while establishing the steady state in this case.
In still another case, it can also be contemplated that a fuel
quality determining mode to positively establish the steady state
is carried out immediately after cold staring in order to determine
the fuel quality.
Since the fuel quality would be maintained without refueling, one
determination operation suffices per ignition on. A determination
operation can be performed once every several ignition ONs. In
another case, it can also be contemplated that the apparatus is
arranged to acquire output of a sensor for detecting the residual
quantity of fuel and perform the fuel quality determination upon
increase of the residual quantity of fuel (i.e., upon refueling).
In either of the cases, it is preferable to carry out the
determination immediately after cold starting, as described
above.
In the example herein, as described above, the output torque of the
engine 1 is not calculated only from the reaction torque Tg of MG 3
but is also calculated from the operational state of the engine 1.
When the separate output torques of the engine 1 are calculated
from the reaction torque Tg of MG 3 and from the operational state
of the engine 1, respectively, in this way, the comparison between
them makes it feasible to determine the fuel quality more
accurately.
Namely, the output torque Te-cal calculated based on the
operational state of the engine 1 is an estimated value of output
torque considered to be outputted in that operational state. In
contrast with it, the output torque Te calculated based on the
reaction torque Tg of MG 3 can be regarded as an actual output
torque from the engine 1. If there is a deviation between them
under comparison, the deviation can be considered to be caused by
the fuel quality. This configuration permits the determination with
higher accuracy than the determination of the fuel quality simply
based on only the reaction torque Tg of MG 3.
Described next is how to reflect the aforementioned determination
of fuel quality in the operation of the engine.
In the case of the hybrid car, the vehicle is driven by combination
of the output of the engine 1 with the output of MG 2 (or by use of
only either one of them in some cases). Therefore, the main ECU 10
generally calculates the driving force necessary for driving the
car and thereafter allocates this necessary driving force into
required part to the engine 1 and required par t to MG 2. After
that, the mai n ECU 10 issues respective drive commands to the
engine ECU 11, to the motor ECU 12, and to the battery ECU 13. The
operation of the engine 1 based on the drive commands will be
described below.
The determined fuel quality is reflected in the fuel injection
quantity of the engine 1. Normally, the fuel injection quantity TAU
is obtained by correcting a basic injected quantity by various
correction factors. The following will describe in order,
calculation of upon-starting fuel injection quantity TAU upon
starting of the engine and calculation of after-starting fuel
injection quantity TAU after starting of the engine.
First, the calculation of the upon-starting fuel injection quantity
TAU will be described.
Since the fuel quality is determined in the operating state of the
engine 1, a previous detection result of fuel quality is used upon
the calculation of the upon-starting fuel injection quantity
TAU.
The upon-starting fuel injection quantity TAU is calculated
according to Eq (5) below.
TAU=TAUST.times.KNEST.times.KBST.times.KPA (5)
In this equation, the upon-starting basic fuel injection quantity
TAUST is determined according to the cooling water temperature THW
of the internal-combustion engine and the fuel quality, and this
upon-starting basic fuel injection quantity TAUST is corrected by
various correction factors described below, thereby finally
obtaining the upon-starting fuel injection quantity TAU. The
upon-starting basic fuel injection quantity TAUST is stored in the
form of a map in the ROM in the engine ECU 11.
A speed correction factor KNEST is determined according to the
rotational speed NE of the engine 1 and is a correction factor for
changing the upon-starting fuel injection quantity TAU according to
the speed NE. A battery voltage correction factor KBST is
determined according to the battery voltage VB. Since a drop of
battery voltage VB results in degradation of performance of the
fuel pump, a shortage of fuel due to this degradation of
performance is compensated for by the battery voltage correction
factor KBST. An atmospheric pressure correction factor KPA is
determined according to the atmospheric pressure PA. Since the air
density (intake air flow) varies depending upon the atmospheric
pressure PA, a change of necessary fuel due to this change of air
density is corrected for by the atmospheric pressure correction
factor KPA.
A flowchart for the calculation of the upon-starting fuel injection
quantity TAU is presented in FIG. 8.
First, the cooling water temperature THW, engine speed NE, battery
voltage VB, and atmospheric pressure PA are read in from the
various sensors (step 200). Then the fuel quality index FQIND
indicating the fuel quality is read in from the backup RAM of the
engine ECU 11 (step 201). From the cooling water temperature THW
and fuel quality index FQIND thus read, the map in the engine ECU
11 is searched to read the upon-starting basic fuel injection
quantity TAUST (step 202). Then the speed correction factor KNEST
is calculated from the engine speed NE (step 203), the battery
voltage correction factor KBST from the battery voltage VB (step
204), and the atmospheric pressure correction factor KPA from the
atmospheric pressure PA (step 205).
Using the upon-starting basic fuel injection quantity TAUST read
from the map, and the calculated speed correction factor KNEST,
battery voltage correction factor KBST, and atmospheric pressure
correction factor KPA, the upon-starting fuel injection quantity
TAU is calculated from Eq (5) above (step 206). Based on the
upon-starting fuel injection quantity TAU thus calculated, the
engine ECU 11 outputs a control signal to the injector expected to
inject the fuel (step 207). In this way, the upon-starting fuel
injection quantity TAU reflects the determined fuel quality (fuel
quality index FQIND) through the upon-starting basic fuel injection
quantity TAUST.
The calculation of the after-starting fuel injection quantity TAU
will be described below.
Immediately after the engine 1 is started based on the above-stated
upon-starting fuel injection quantity TAU, another detection of
fuel quality must be carried out. The after-starting fuel injection
quantity TAU is calculated based on the fuel quality newly
determined immediately after the starting of the engine 1.
When the engine speed NE exceeds a predetermined value after
starting of the engine 1, the after-starting fuel injection
quantity TAU is calculated according to the following equation.
In this equation, a basic fuel injection quantity TP is determined
according to the intake air flow Q and the speed NE of the
internal-combustion engine and this basic fuel injection quantity
TP is corrected by various correction factors described below,
thereby finally obtaining the after-starting fuel injection
quantity TAU. The basic fuel injection quantity TP is stored in the
form of a map in the ROM in the engine ECU 11.
A warm-up and high-load correction factor FWLOTP is a factor for
correcting the fuel injection quantity during warming-up or during
high-load operation. An air-fuel ratio feedback correction factor
FAF is a factor for bringing the air-fuel ratio of the engine 1 to
a predetermined target air-fuel ratio, based on the output of the
fuel-air ratio sensor 26 mounted on the exhaust pipe 31. A
wall-attaching fuel correction factor FMW is determined according
to the intake pressure PM and the fuel quality and is a factor for
correcting the fuel injection quantity in consideration of a
balance between attaching amount of fuel onto the wall surfaces in
the intake pipe and the cylinders and detaching amount of fuel from
the wall surfaces in the intake pipe and the cylinders. When the
operation of the engine 1 is in the transient state, the balance is
degraded between the attaching amount of fuel onto the wall
surfaces in the intake pipe and the cylinders and the detaching
amount of fuel from the wall surfaces in the intake pipe and the
cylinders and the fuel injection quantity is thus corrected by the
wall-attaching fuel correction factor FMW.
The warm-up or high-load correction factor FWLOTP is a factor for
increasing the fuel injection quantity to implement stable
combustion, because atomization of fuel becomes poor during
warming-up, and for increasing the fuel injection quantity to
decrease the exhaust-gas temperature by atomization of fuel,
because the exhaust-gas temperature becomes high during high-load
operation, and it is calculated according to Eq (7) below.
A warm-up increase correction factor FWLB is determined according
to the cooling water temperature THW and the fuel quality and is
stored in the form of a map in the ROM in the engine ECU 11. A
warm-up increase damping factor FLWD is a factor for gradually
damping the increase due to the warm-up or high-load correction
factor FWLOTP and factor free of the influence of the fuel
quality.
A warm-up increase speed correction factor KWL is determined
according to the engine speed NE and is a factor for correcting the
increase due to the warm-up or high-load correction factor FWLOTP,
according to the speed of the engine 1. The warm-up increase speed
correction factor KWL is also a factor free of the influence of the
fuel quality. An after-starting increase correction factor FASE is
determined according to the cooling water temperature THW and the
fuel quality and is a correction factor for increasing the fuel
quantity by a quantity shortage due to attachment of fuel to the
wall surfaces in the dry intake pipe and cylinders immediately
after starting of the engine 1, and is stored in the form of a map
in the ROM in the engine ECU 11. The after-starting increase
correction factor FASE is gradually damped.
A flowchart for the calculation of the after-starting fuel
injection quantity TAU is presented in FIG. 9.
First, the intake air flow Q and engine speed NE are read in from
the various sensors (step 300), and from the intake air flow Q and
engine speed NE thus read, the map in the engine ECU 11 is searched
to read the basic fuel injection quantity TP (step 301). In certain
cases the basic fuel injection quantity TP is determined from the
intake pressure PM and the engine speed NE. Then the warm-up or
high-load correction factor FWLOTP, air-fuel ratio feedback
correction factor FAF, and wall-attaching fuel correction factor
FMW are calculated in order (steps 302 to 304). The calculation of
the warm-up or high-load correction factor FWLOTP, air-fuel ratio
feedback correction factor FAF, and wall-attaching fuel correction
factor FMW will be described later.
Using the basic fuel injection quantity TP read from the map, and
the calculated warm-up and high-load correction factor FWLOTP,
air-fuel ratio feedback correction factor FAF, and wall-attaching
fuel correction factor FMW, the after-starting fuel injection
quantity TAU is calculated from above Eq (6) (step 305). Based on
the after-starting fuel injection quantity TAU thus calculated, the
engine ECU 11 outputs a control signal to the injector expected to
inject the fuel (step 306).
FIG. 10 shows a flowchart for the calculation of the warm-up or
high-load correction factor FWLOTP in step 302 described above.
First, the cooling water temperature THW and engine speed NE are
read in from the various sensors (step 400). The fuel quality index
FQIND indicating the fuel quality is then read in from the backup
RAM of the engine ECU 11 (step 401). From the cooling water
temperature THW and fuel quality index FQIND thus read, the map in
the engine ECU 11 is searched to read the warm-up increase
correction factor FWLB (step 402). Then the warm-up increase speed
correction factor KWL is calculated from the engine speed NE (step
403) and the after-starting increase correction factor FASE is also
calculated (step 404). The calculation of the after-starting
increase correction factor FASE will be described later.
Using the warm-up increase correction factor FWLB read from the
map, the predetermined warm-up increase damping factor FLWD, and
the calculated warm-up increase speed correction factor KWL and
after-starting increase correction factor FASE, the warm-up or
high-load correction factor FWLOTP is calculated from above Eq (7)
(step 405).
The calculation of the after-starting increase correction factor
FASE in step 404 described above is presented in FIG. 11.
First, the cooling water temperature THW is read in from the sensor
(step 500), and the fuel quality index FQIND indicating the fuel
quality is read in from the backup RAM of the engine ECU 11 (step
501). From the cooling water temperature THW and fuel quality index
FQIND thus read, the map in the engine ECU 11 is searched to read
the after-starting increase correction factor FASE (step 502). The
after-starting increase correction factor FASE read from the map is
gradually damped using the predetermined after-starting increase
damping factor KASE (steps 503, 504). If in step 504 the
after-starting increase correction factor FASE damped becomes
negative, the after-starting increase correction factor FASE is set
to 0 (step 505).
Next, FIG. 12 shows a flowchart for the calculation of the air-fuel
ratio feedback correction factor FAF in step 303 described
above.
The routine illustrated in FIG. 12 is repeatedly carried out at
every predetermined time (e.g., every several milliseconds). The
air-fuel ratio sensor 26 for detecting the air-fuel ratio of the
engine 1 from the oxygen concentration in the exhaust gas or the
like is mounted on the exhaust pipe 31 of the engine 1. The
air-fuel ratio feedback correction factor FAF is generated based on
the output of this air-fuel ratio sensor 26 and the after-starting
fuel injection quantity TAU is corrected based on the air-fuel
ratio feedback correction factor FAF generated. An oxygen sensor is
commonly used as the air-fuel ratio sensor. The oxygen sensor can
determine whether the air-fuel ratio of the engine 1 is richer or
leaner than the stoichiometric ratio, from the oxygen concentration
in the exhaust gas.
When the air-fuel ratio is leaner than the stoichiometric ratio (a
lean air-fuel ratio), the air-fuel ratio feedback correction factor
FAF is increased (i.e., is made gradually richer). When the
air-fuel ratio is richer than the stoichiometric ratio (a rich
air-fuel ratio), the air-fuel ratio feedback correction factor FAF
is decreased (i.e., is made gradually leaner). Since in this way
the after-starting fuel injection quantity TAU is controlled by the
feedback control based on the air-fuel ratio feedback correction
factor FAF according to the detection result of the air-fuel ratio
sensor 26, the air-fuel ratio can be maintained near the target
air-fuel ratio (normally, the stoichiometric ratio) even if there
is a small error in the air flow meter for detecting the intake air
flow Q, for example.
First, it is determined whether an execution condition is met for
the feedback (F/B) control based on the air-fuel ratio feedback
correction factor FAF (step 600). The F/B control execution
condition is, for example, that the air-fuel ratio sensor 26 is
active (the oxygen sensor or the like as the air-fuel ratio sensor
has to be brought to a predetermined activation temperature in
order to exhibit its function), that the warm-up operation is
complete, and so on. When the F/B control execution condition is
not met, i.e., when step 600 ends up with no, the air-fuel ratio
feedback correction factor FAF is set to 1.0 (step 628), and this
routine is terminated.
When the F/B control execution condition is met, i.e., when step
600 ends up with yes, the output of the air-fuel ratio sensor 26 is
read in order to carry out the F/B control based on the air-fuel
ratio feedback correction factor FAF (step 601), and it is first
determined whether the sensor output signal is a lean air-fuel
ratio or a rich air-fuel ratio (step 602). Then an air-fuel ratio
flag F1 for switching of the air-fuel ratio feedback correction
factor FAF is generated in steps 603 to 608 and in steps 609 to
614.
The air-fuel ratio flag F1 is switched from lean (F1=0) to rich
(F1=1) when rich signals from the output of the air-fuel ratio
sensor 26 continue from a predetermined delay time TDR; or it is
switched from rich (F1=1) to lean (F1=0) when lean signals from the
output of the air-fuel ratio sensor 26 continue for a predetermined
delay time TDL (steps 603 to 614). A delay counter CDLY is used for
counting these delay times TDR, TDL.
Then, based on whether this air-fuel ratio flag F1 is lean (F1=0)
or rich (F1=1) and based on whether the air-fuel ratio flag F1 was
inverted (F1=0.fwdarw.1 or F1=1.fwdarw.0) immediately before, the
air-fuel ratio feedback correction factor FAF is generated in steps
615 to 627.
At this time, immediately after the air-fuel ratio flag F1 is
judged as having been inverted (step 615), the air-fuel ratio
feedback correction factor FAFR or FAFL at that time is once set to
FAF (steps 617, 618), and thereafter the air-fuel ratio feedback
correction factor FAF is varied in a skipping manner (steps 619,
620). A skipping amount RSL is one used when the air-fuel ratio
flag F1 was inverted from lean to rich (F1=0.fwdarw.1). A skipping
amount RSR is one used when the air-fuel ratio flag F1 was inverted
from rich to lean (F1=1.fwdarw.0). The air-fuel ratio feedback
correction factor FAF is varied in the skipping manner immediately
after the inversion of the air-fuel ratio flag F1 in this way, in
order to enhance the response of air-fuel ratio control.
When the air-fuel ratio flag F1 maintains the value of either lean
(F=0) or rich (F=1), the air-fuel ratio feedback correction factor
FAF is gradually increased or decreased by a change KIR or KIL, as
described above (steps 621 to 623). The change KIR is a unit
increase amount used when the air-fuel ratio flag F1 is lean
(F1=0). The change KIL is a unit decrease amount used when the
air-fuel ratio flag F1 is rich (F1=1). For the air-fuel ratio
feedback correction factor FAF, the lower limit thereof is guarded
in steps 624, 625, and the upper limit thereof in steps 626,
627.
FIG. 13 shows an example of changes of the output A/F (after A/D
conversion) of the air-fuel ratio sensor 26, delay counter CDLY,
air-fuel ratio flag F1, and air-fuel ratio feedback correction
factor FAF, in the air-fuel ratio feedback control described
above.
The reason why the air-fuel ratio feedback correction factor FAF is
not generated directly based on the output of the air-fuel ratio
sensor 26 but through the air-fuel ratio flag F1, is that the
air-fuel ratio is prevented from being disturbed when the
predetermined time TDR, -TDL is made in consideration of the
response of the air-fuel ratio sensor 26 or when the output of the
air-fuel ratio sensor 26 is switched between lean and rich in a
short time (see the right part of FIG. 13).
Further, a flowchart for the calculation of the wall-attaching fuel
correction factor FMW in step 304 is presented in FIG. 14.
First, the intake pressure PM and engine speed NE at the closed
position of the intake valve are read in from the respective
sensors (step 700), and fuel attaching amount QMW with the engine 1
being operated in the steady state at this intake pressure PM, is
read from the map in the engine ECU 11 (step 701). The fuel quality
index FQIND indicating the fuel quality is read from the backup RAM
of the engine ECU 11 (step 702), and from the fuel quality index
FQIND thus read, the map in the engine ECU 11 is searched to read
the fuel quality correction factor FQLTY (step 703).
Next, based on the fuel attaching amount QMW thus calculated, a
fuel attachment change DLQMW is calculated according to Eq (8)
below (step 704).
DLQMW=(QMW-QMW.sub.-720).times.KNE (8)
Here QMW.sub.-720 is a fuel attaching amount before 720.degree. CA.
A rotational speed correction factor KNE is a correction factor
determined according to the engine speed NE.
The fuel attachment change DLQMW calculated is a change amount of
fuel attaching to the wall surfaces. This change amount is one in
several injections and thus this is corrected into one for each of
the several injections. The fuel attachment change DLQMW is reduced
to a reduced amount fDLQMW per injection (step 705). The detailed
description is omitted herein for the method of calculating the
reduced amount fDLQMW from the fuel attachment change DLQMW. The
wall-attaching fuel correction factor FMW is calculated from the
reduced amount fDLQMW and the fuel quality correction factor FQLTY
(step 706). As described, the after-starting fuel injection
quantity TAU reflects the determined fuel quality (fuel quality
index FQIND) through the warm-up or high-load correction factor
FWLOTP and the wall-attaching fuel correction factor FMW.
The determination of fuel quality described above was one made in
the steady state. The following will describe determination of fuel
quality in the transient state.
In the example below, the detection of fuel quality can be
implemented in the other states than the steady state as long as
the engine 1 is under combustion, excluding such non-combustion
periods of the engine 1 as stop periods, cranking periods, fuel cut
periods, and so on.
A flowchart of the fuel quality determining process in the
transient state is presented in FIG. 15. The fuel quality
determining process in the transient state will be described below
along FIG. 15.
First, it is determined whether the engine 1 is in operation (step
800), and with the engine 1 in operation, it is determined whether
the fuel is cut (step 801). Unless the fuel is cut, the angular
velocity .omega.e of rotation of the engine 1 and the angular
velocity .omega.g of rotation of MG 3 are read in (step 802).
Then the reaction torque Tg of MG 3 is detected (step 803) and the
output torque Te of the engine 1 is calculated using aforementioned
Eq (4) from the reaction torque Tg of MG 3, the angular velocity
.omega. of the engine 1, and the angular velocity .omega.g of Mg 3
(step 804). It is then determined whether the engine is in the
warm-up operation (step 805). Since the fuel quality can be
determined more accurately during the warm-up operation immediately
after cold starting as described above, this routine is configured
to determine whether the engine is in the warm-up operation and
then detect the fuel quality if the engine is in the warm-up
operation.
When the engine is in the warm-up operation, the operational state
of the engine 1 is determined based on at least one value of the
cooling water temperature, intake air flow, engine speed, air-fuel
ratio, and injection timing in order to detect the fuel quality,
and the output torque Te-cal of the engine 1 is also calculated
from this operational state (step 806). Then the difference is
calculated between the output torque Te-cal calculated based on the
operational state and the output torque Te of the engine 1
calculated based on the reaction torque Tg of MG 3 and it is then
determined whether the difference is greater than a preset
reference (step 807).
When the difference between the output torque Te-cal calculated
based on the operational state of the engine 1 and the output
torque Te of the engine 1 calculated based on the reaction torque
Tg of MG 3 is greater than the set reference, the fuel is judged as
being heavy and the fuel quality index FQIND is set to 1, which is
stored in the backup RAM in the main ECU 10 (step 808). On the
other hand, when the difference between the output torque Te-cal
calculated based on the operational state of the engine 1 and the
output torque Te of the engine 1 calculated based on the reaction
torque Tg of MG 3 is smaller than the set reference, the fuel is
not considered to be heavy and thus the fuel quality index FQIND is
set to 0, which is stored in the backup RAM in the main ECU 10
(step 809).
The fuel quality thus determined is reflected in the operation of
the engine 1 thereafter. How the determination of fuel quality
described above is reflected in the operation of the engine, was
described previously and the description thereof is omitted
herein.
The car described above was the so-called hybrid car as a merger of
the series system and the parallel system, but the invention is
also applicable to hybrid cars of the series system and hybrid cars
of the parallel system. The present invention can also be applied
to the other cars than the hybrid cars if they are equipped with a
generator for generating electric power while receiving the output
of the internal-combustion engine. Further, correction with other
correction factors not described may be carried out in the
aforementioned calculation of fuel injection quantity TAU.
The output torque Te of the engine 1 can be calculated from the
reaction torque Tg of MG 3, using the predetermined relations like
Eqs (3), (4) between the output torque Te of the engine 1 and the
reaction torque Tg of MG 3, and the fuel quality can be determined
accurately through the reaction torque Tg of MG 3.
The fuel quality can be determined accurately from the reaction
torque Tg of MG 3 even when the engine 1 is operated as maintained
in the predetermined region of high energy efficiency by
maintaining the speed of the engine 1 in the predetermined region
by the rotation control. Even in such a case that the rotation
control is carried out with little change in the rotational speed
against the difference of the fuel quality, as described above, the
fuel quality can be determined accurately.
The fuel determining means has the first torque calculating means
and second torque calculating means described above and the fuel
quality is determined based on the comparison between the output
torques of the engine 1 detected by the respective torque detecting
means, whereby more accurate detection can be carried out.
Industrial Applicability
The output state detecting apparatus of internal-combustion engine
according to the present invention is able to detect the output
state of the internal-combustion engine from the reaction torque of
the motor and is thus suitable for detecting the output state of
the internal-combustion engine, e.g., in the cars equipped with the
internal-combustion engine and the motor.
* * * * *